Pluto was once called a planet.
冥王星以前，被叫做行星。
Later, scientists changed their minds.
后来呀，科学家们改了主意。
Now we call it a dwarf planet.
现在它叫“矮行星”啦。
Pluto is really very small.
冥王星的个头，真的很小。
It is even smaller than our moon.
它比我们的月亮，还要小一圈。
The moon is wider than Pluto.
月亮的直径，比冥王星还大。
So it lost its old planet title.
就这样，它丢掉了行星的头衔。
